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Aim: How do we find the the tangent of the sum of two angles and the tangent of the difference of two angles? (This formula will be given on the Regents Reference sheet)

At the end of this lesson, you will be able to...

1. apply the sum and difference formulas for sine and cosine to discover the formulas for the tangent of the sum of two angles and the tangent of the difference of two angles
2. apply the tangent sum and the tangent difference formulas to find exact values of problems
3. state the tangent sum and the tangent difference formulas in words.

Copy down these questions into your notebooks. Answer them as you watch the video.

1. What is the tangent sum formula?
2. What is the tangent difference formula?

Video

• Classwork: Answer the following questions in your notebook. Be sure to give the exact value. Use your calculator to check your answer

1. Find the exact value of tan 165 degrees. (Ans: -2 + sqrt3)
2. Find the exact value of 7pi/4 (Ans: -1)

• Homework: Do numbers 4-26 even

Tan_sum_and_difference.JPG

• Answers:

A-Tan_sum_and_diff.JPG

• Journal entry: Explain how to derive the formula for cot (A + B). You can search online for help.